Changing the flexible clutch pipe

I need to replace my flexible clutch pipe, however, when I try to undo either end, the flexible tube starts to twist up. In other words as I undo the nut the tube goes around with it. Undoing a bit each side doesn't help. There must be an easier way. I could just cut the tube but I assume I'm going to have the same problem installing the new one.

flexi pipe has spanner flats on other side of bracket securing it

Thanks for the quick reply.... I'd slackened off the spanner flats but still when I undo the main nut the tube curls up. I must be doing something wrong?

you need 2 spanners one to hold pipe other for nut

Ok - got it - I'd undone the spanner nut but was trying to undo the nut on the tube rather than the nut on the pipe. Tube off now, awaiting replacement.
Thanks for the tip.